InterNano Nanomanufacturing Repository
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The Nanomaterial Data Curation Initiative: A collaborative approach to assessing, evaluating, and advancing the state of the field
No full textThe Nanomaterial Data Curation Initiative (NDCI), a project of the National Cancer Informatics Program Nanotechnology Working Group (NCIP NanoWG), explores the critical aspect of data curation within the development of informatics approaches to understanding nanomaterial behavior. Data repositories and tools for integrating and interrogating complex nanomaterial datasets are gaining widespread interest, with multiple projects now appearing in the US and the EU. Even in these early stages of development, a single common aspect shared across all nanoinformatics resources is that data must be curated into them. Through exploration of sub-topics related to all activities necessary to enable, execute, and improve the curation process, the NDCI will provide a substantive analysis of nanomaterial data curation itself, as well as a platform for multiple other important discussions to advance the field of nanoinformatics. This article outlines the NDCI project and lays the foundation for a series of papers on nanomaterial data curation. The NDCI purpose is to: 1) present and evaluate the current state of nanomaterial data curation across the field on multiple specific data curation topics, 2) propose ways to leverage and advance progress for both individual efforts and the nanomaterial data community as a whole, and 3) provide opportunities for similar publication series on the details of the interactive needs and workflows of data customers, data creators, and data analysts. Initial responses from stakeholder liaisons throughout the nanoinformatics community reveal a shared view that it will be critical to focus on integration of datasets with specific orientation toward the purposes for which the individual resources were created, as well as the purpose for integrating multiple resources. Early acknowledgement and undertaking of complex topics such as uncertainty, reproducibility, and interoperability is proposed as an important path to addressing key challenges within the nanomaterial community, such as reducing collateral negative impacts and decreasing the time from development to market for this new class of technologies
Antimicrobial surfaces containing cationic nanoparticles: How immobilized, clustered, and protruding cationic charge presentation affects killing activity and kinetics
No full textThis work examines how the antimicrobial (killing) activity of net-negative surfaces depends on the presentation of antimicrobial cationic functionality: distributed versus clustered, and flat clusters versus raised clusters. Specifically, the ability to kill Staphylococcus aureus by sparsely distributed 10 nm cationic nanoparticles, immobilized on a negative surface and backfilled with a PEG (polyethylene glycol) brush, was compared with that for a dense layer of the same immobilized nanoparticles. Additionally, sparsely distributed 10 nm poly-L-lysine (PLL) coils, adsorbed to a surface to produce flat cationic "patches" and backfilled with a PEG brush were compared to a saturated adsorbed layer of PLL. The latter resembled classical uniformly cationic antimicrobial surfaces. The protrusion of the cationic clusters substantially influenced killing but the surface concentration of the clusters had minor impact, as long as bacteria adhered. When surfaces were functionalized at the minimum nanoparticle and patch densities needed for bacterial adhesion, killing activity was substantial within 30 min and nearly complete within 2 h. Essentially identical killing was observed on more densely functionalized surfaces. Surfaces containing protruding (by about 8 nm) nanoparticles accomplished rapid killing (at 30 min) compared with surfaces containing similarly cationic but flat features (PLL patches). Importantly, the overall surface density of cationic functionality within the clusters was lower than reported thresholds for antimicrobial action. Also surprising, the nanoparticles were far more deadly when surface-immobilized compared with free in solution. These findings support a killing mechanism involving interfacial stress
A step toward next-generation nanoimprint lithography: extending productivity and applicability
No full textBecause of its unique principle based on mechanical deformation, nanoimprint lithography (NIL) has been playing an important role for nanopatterning and nanofabrication beyond the limit of conventional optical lithography. Many diverse fields involving electronics, photonics, and energy engineering have all shown significant increase in utilization of nanopattern structures, particularly in large areas and at submicron scales. To meet this demand, expanding the realm of NIL toward more scalable and versatile patterning technology is in high demand. In this feature article, we give an overview of how NIL can extend productivity and applicability by addressing three key issues: continuous NIL for more scalable nanopatterning, large-area mold fabrications, and novel resist engineering
Resonator- and Filter-Induced Slow Waves for High-Sensitivity RF Interferometer Operations
No full textResonators and filters have engineered radio-frequency (RF) spectrums and dispersions, which induce slow waves for increased local RF field intensities and prolonged field propagations. When used for sensors, the interactions between RF waves and material-under-test (MUT) can be significantly strengthened due to enhanced RF fields and longer interaction time when compared with uniform transmission lines. In this paper, a microstrip resonator (MR) and a coupled line (CL) filter are designed and incorporated into an interferometer. The obtained results are compared with that of a coplanar waveguide-based interferometer. Both simulated and measured results show that the MR and CL can significantly enhance RF interferometer sensitivity, e.g., by >5 times of frequency shift and up to 40-dB more of transmission coefficient change similar to 2 GHz. Further work is needed to fully understand the physical processes and obtain quantitative MUT permittivity properties from the measured scattering parameters
Concentric circle scanning system for large-area and high-precision imaging
No full textLarge-area manufacturing surfaces containing micro-and nanoscale features and large-view biomedical targets motivate the development of large-area, high-resolution and high-speed imaging systems. Compared to constant linear velocity scans and raster scans, constant angular velocity scans can significantly attenuate transient behavior while increasing the speed of imaging. In this paper, we theoretically analyze and evaluate the speed, acceleration and jerks of concentric circular trajectory sampling (CCTS). We then present a CCTS imaging system that demonstrates less vibration and lower mapping errors than raster scanning for creating a Cartesian composite image, while maintaining comparably fast scanning speed for large scanning area. (C) 2015 Optical Society of Americ
Experimental realization of crossover in shape and director field of nematic tactoids
No full textSpindle-shaped nematic droplets (tactoids) form in solutions of rod-like molecules at the onset of the liquid crystalline phase. Their unique shape and internal structure result from the interplay of the elastic deformation of the nematic and anisotropic surface forces. The balance of these forces dictates that tactoids must display a continuous variation in aspect ratio and director-field configuration. Yet, such continuous transition has eluded observation for decades: tactoids have displayed either a bipolar configuration with particles aligned parallel to the droplet interface or a homogeneous configuration with particles aligned parallel to the long axis of the tactoid. Here, we report the first observation of the continuous transition in shape and director-field configuration of tactoids in true solutions of carbon nanotubes in chlorosulfonic acid. This observation is possible because the exceptional length of carbon nanotubes shifts the transition to a size range that can be visualized by optical microscopy. Polarization micrographs yield the interfacial and elastic properties of the system. Absorbance anisotropy measurements provide the highest nematic order parameter (S = 0.79) measured to date for a nematic phase of carbon nanotubes at coexistence with its isotropic phase
A functional assay-based strategy for nanomaterial risk forecasting
No full textThe study of nanomaterial impacts on environment, health and safety (nanoEHS) has been largely predicated on the assumption that exposure and hazard can be predicted from physical–chemical properties of nanomaterials. This approach is rooted in the view that nanoöbjects essentially resemble chemicals with additional particle-based attributes that must be included among their intrinsic physical–chemical descriptors. With the exception of the trivial case of nanomaterials made from toxic or highly reactive materials, this approach has yielded few actionable guidelines for predicting nanomaterial risk. This article addresses inherent problems in structuring a nanoEHS research strategy based on the goal of predicting outcomes directly from nanomaterial properties, and proposes a framework for organizing data and designing integrated experiments based on functional assays (FAs). FAs are intermediary, semi-empirical measures of processes or functions within a specified system that bridge the gap between nanomaterial properties and potential outcomes in complex systems. The three components of a functional assay are standardized protocols for parameter determination and reporting, a theoretical context for parameter application and reference systems. We propose the identification and adoption of reference systems where FAs may be applied to provide parameter estimates for environmental fate and effects models, as well as benchmarks for comparing the results of FAs and experiments conducted in more complex and varied systems. Surface affinity and dissolution rate are identified as two critical FAs for characterizing nanomaterial behavior in a variety of important systems. The use of these FAs to predict bioaccumulation and toxicity for initial and aged nanomaterials is illustrated for the case of silver nanoparticles and Caenorhabditis elegans
Surfaces for Competitive Selective Bacterial Capture from Protein Solutions
No full textActive surfaces that form the basis for bacterial sensors for threat detection, food safety, or certain diagnostic applications rely on bacterial adhesion. However, bacteria capture from complex fluids on the active surfaces can be reduced by the competing adsorption of proteins and other large molecules. Such adsorption can also interfere with device performance. As a result, multiple upstream processing steps are frequently employed to separate macromolecules from any cells, which remain in the buffer. Here, we present an economical approach to capture bacteria, without competitive adsorption by proteins, on engineered surfaces that do not employ biomolecular recognition, antibodies, or other molecules with engineered sequences. The surfaces are based on polyethylene glycol (PEG) brushes that, on their own, repel both proteins and bacteria. These PEG brushes backfill the surface around sparsely adsorbed cationic polymer coils (here, poly-r.-lysine (PLL)). The PLL coils are effectively embedded within the brush and produce locally cationic nanoscale regions that attract negatively charged regions of proteins or cells against the steric background repulsion from the PEG brush. By carefully designing the surfaces to include just enough PLL to capture bacteria, but not enough to capture proteins, we achieve sharp selectivity where S. aureus is captured from albumin- or fibrinogen-containing solutions, but free albumin or fibrinogen molecules are rejected from the surface. Bacterial adhesion on these surfaces is not reduced by competitive protein adsorption, in contrast to performance of more uniformly cationic surfaces. Also, protein adsorption to the bacteria does not interfere with capture, at least for the case of S. aureus, to which fibrinogen binds through a specific receptor